A Laser Warning Receivers (LWRs) is a type of warning system used as a passive military defense. It detects laser emission from laser guidance systems and laser rangefinders. Then it alerts the crew and can start various countermeasures, like smoke screen, aerosol screen, active Laser Self-Defense Weapon (LSDW) with Laser dazzler, laser jammer, etc.
A method for determining azimuth and elevation angles of a radiation source or other physical objects located anywhere within an cylindrical field of view is disclosed in U.S. Pat. No. 7,075,048 issued to Gal et al. The method makes use of an omni-directional imaging system comprising of reflective surfaces, an image sensor and an optional optical filter for filtration of the desired wavelengths. The imaging system is designed to view an omni-directional field of view using a single image sensor and with no need for mechanical scan for coverage of the full field of view. Use of two such systems separated by a known distance, each providing a different reading of azimuth and elevation angle of the same object, enables classic triangulation for determination of the actual location of the object. This prior art refers specifically to the design and use of reflective surfaces to achieve a panoramic omni-directional radiation source locator.
In another prior art, AN/AAR-47 Missile Approach Warning System (MAWS) employed on helicopters and transport aircraft is disclosed. The system warns of threat missile approach by detecting radiation associated with the rocket motor and automatically initiates flare ejection. The AN/AAR-47 is a passive Electro-Optic Missile Warning System designed to provide warning of Surface to Air Missiles (SAMS) and pass information to countermeasures systems. Employed on helicopters and transport aircraft, the AAR-47 Missile Approach Warning System (MAWS) warns of threat missile approach, enabling the effective employment of evasive maneuvers and electronic and infrared countermeasures. Detection algorithms are used to discriminate against non-approaching radiation sources. The system consists of four sensor assemblies housed in two or more sensor domes, a central processing unit, and a control indicator. The Warning System provides attacking missile declaration and sector direction finding and will be interfaced directly to the ALE-39/47 countermeasures dispenser. Without the AAR-47, helicopters and fixed-wing aircraft have no infrared missile detection system. However, this AAR-47 comprises a distributed staring sensor which can be rather expensive.
A need, therefore, exists for a low cost, wrap-around laser′ warning with one sensor to accurately determine the angle of arrival.